Medical advances during the past two decades in the diagnosis and treatment of individuals with Cystic Fibrosis (CF) have resulted in improved survival. As such, healthcare professionals are now treating a new population, adults, with their own barriers to successful illness management. Treatment adherence is an important factor in successful illness management. The regimen, however, is a complex home treatment program that requires time and special skills to perform. Moreover, the stress of adhering to the treatment regimen, combined with the progressive and terminal nature of CF, places an emotional burden on the individual. This is, however, an under-researched area, particularly in exploring how psychosocial factors may relate to subsequent treatment adherence. Research in this area would lead to significant improvement in the understanding of and interventions to improve the psychological adjustment, disease management, quality of life, and health outcomes for adults with CF. Thus, the specific aims of this study are to (1) evaluate the relationship between psychosocial factors (e.g., depression, anxiety, social support, and coping) and adults with CF?s levels of adherence and (2) describe and characterize adherence behaviors of adults with CF.